Brown dwarfs should be regarded as third class of celestial bodies after stars and planets

August 23rd, 2008 - 3:33 pm ICT by ANI  

Washington, August 23 (ANI): Researchers at the Argelander Institute of Astronomy of the University of Bonn in Germany have discovered that brown dwarfs, which may be stellar miscarriages, need to be treated as a separate class of celestial bodies, in addition to stars and planets.

Brown dwarfs (or BDs) are what scientists call objects which populate the galaxies apart from the stars.

Unlike the latter, they cannot develop high-yield hydrogen fusion as in the interior of our sun due to their low mass (less than about 8% of the suns mass).

But in addition to this, brown dwarfs and stars also seem to be different in their mating behaviour.

Stars often occur in pairs, which dance around each other. The intimacy which this dance involves, however, varies a great deal: sometimes the gap is smaller than one radius of the Earths orbit (also known as Astronomical Unit or AU).

However, the two partners can also keep apart by as much as many thousands of AUs.

Things are different with brown dwarfs, astrophysicist Ingo Thies of the Bonn Argelander Institute of Astronomy explains. The orbital radiuses of BD pairs are cut off above about 15 AUs; BD pairs with greater distances are the exception, he said.

What is more, there are hardly any mixed pairs consisting of suns and brown dwarfs far fewer than expected. This phenomenon is also known as brown dwarf desert.

According to the classical model, there ought not to be these differences, Professor Pavel Kroupa of the Argelander Institute explained.

According to this, both brown dwarfs and stars ought to emerge from interstellar clouds of gas which become concentrated because of the attraction of their mass. But if this was the case, these celestial bodies should behave in similar ways, he said.

Despite this contradiction, the astronomic community has previously stuck to the theory of a joint origin.

However, Ingo Thies and Pavel Kroupa have now shown empirically for the first time that brown dwarfs must be seen as a class of objects which is separate from the stars.

For this, we analysed the masses of newly born stars, said Ingo Thies. This revealed a jump in the distribution of mass which makes the division in the stellar population apparent, he added.

According to all the theories, brown dwarfs can only emerge at the birth of stars similar to the situation with planets, incidentally.

Thus, there are presumably three quite different celestial bodies: planets, brown dwarfs and stars. (ANI)

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